The invention relates generally to surface modified electrodes using amine-substituted polymeric materials, and electronic devices produced from the modified electrodes.
Electro-active materials, such as electro-active organic materials are used for producing various types of electronic devices, such as organic light emitting devices (OLEDs), photodetectors, and photovoltaic devices. Generally, the electronic devices, such as OLEDs, require low work function metals, such as calcium, magnesium, and the like to facilitate charge injection into the electro-active materials. A problem with the use of low work function metals is their high reactivity toward ambient air and moisture, which often requires that fabrication and operation of these devices be conducted under hermetic conditions or the devices be rigorously encapsulated. To overcome or alleviate these difficulties, it is desirable to employ less reactive metals such as aluminum, gold, silver, and the like as electrodes. However, due to the considerable mismatch of their Fermi-level to the lowest unoccupied molecular orbital (LUMO) of the state-of-the-art electro-active materials, the less reactive metals lead to less efficient electron injection. As a result, devices employing these less reactive metals as electrode materials generally operate at relatively higher voltages and exhibit poorer quantum and power efficiency. In order to circumvent this problem, various electrode activation methods have been employed. One such method for activating metal electrodes is to insert a layer of insulating materials, such as alkali metal fluorides in between the electro-active material and the less reactive metal electrode. However, the application of the activation layer in the most of state-of-the-art devices can be only achieved via thermal evaporation under high vacuum, and does not lend itself to large area, high throughput processing.
Therefore, there is a need to provide functional organic materials that lower the injection barrier, thereby allowing for efficient charge flow between the electrodes and an adjacent electro-active material and, at the same time, substantially preserving the long-term stability and performance of the device. Further, there is a need for methods for using such functional organic materials for producing modified electrodes, which in turn can be used for making electronic devices, for example.